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how would one modify the FK408 to use a 3.5mm mic jack instead of the default microphone sensor. I want to connect a 3.5mm headphone jack cable between my smartphone and the FK408 board so that when the phone plays noises through the mic jack it turns on some 12v led lights.

I have tried simply removing the microphone and replacing it with a 3.5mm headphone jack cable but it does not work. someone told me resistors needed to be changed, but I do not know much about circuit and need basic infomration to change the circuit.